Two different positions of the same dice are shown, the six faces of which are numbered from 1 to 6. When '3' is at the bottom, which number will be on the top?

4

The common numbers in both dices are 1 and 4.

2 is opposite to 5,

And, if we rotate the dice and as it is given in the question '3' is at the bottom, then number 4 will be opposite to it.

Thus, 04 is correct.